How do you know what their potential is? There are many, MANY players who are not seen on top-prospect lists while they're in the 18-21 year old range.

Hell, I remember Magglio Ordonez finally pop up at #56 in BA's top 100 when he was 24 years old.

Wouldn't that have been exactly what my last statement was, that if you go by this belief you can to say everyone has front-line potential.

In terms of why I believe they don't, I enjoy following the minors and scouting reports, and while I like their arms, I personally think at this point they project more as power relievers than starters. They are still being stretched out and haven't had the body of work (or the physical maturation yet) to show if the stuff tool can be sharp in the 7th, 8th, 9th etc.